Manufacture of soap



Patented Nov, 10, 1931 UNITED STATES PATENT OFFICE EUGENE SCHUCK, OF LOSANGELES, CALIFORNIA, ASSIGNOIR. OF ONE-FOURTH TO GEORGE E. MCCREERY, DELOS ANGELES, CALIFORNIA MANUFACTURE or-s'onr No Drawing.

This invention relates to an improved method for the manufacture of.soaps of high soap content and low water content and which are moreoverstable and durable.

The ordinary methods of soap manufacture result in the production ofsoap of high water content. In order to produce soap of high soap andlow water content, the soap of high water content has been subjected toa drying operation. In general, two methods of procedure have beenfollowed in making soap of high soap content and low water content.According to 'one method, the fatty material is saponified in largekettles, with boiling and final settling .of the soap, which is then runover cooling rolls, shredded and dried in a suitable dryer. Ac cordingto the other and older method, the hot soap from the soap kettle iscooled in frames, cut into slabs and bars, shredded with the socalledchipper, and placed on drying screens to be dried, either byletting itstay on these screens long enough or by putting the screens into adrying chamber. Soap can be produced according to these and othermethods qtt manufacture which contains a high percentage of soap and alow water content, but they involve expensive drying and otheroperations, as well as costly machinery, and they consume a great dealof time.

The present invention provides an improved method in which suchobjectionable drying and other operations are eliminated or greatlysimplified, and in whicha soap of high soap content is directly producedin a simple and advantageous manner.'

I have found that if glycerides of animal or vegetable origin andcontaining a varying percentage of free fatty acids are intimately mixedwith alimited amount of water, sufficient to dissolve the caustic alkaliemployed, and finely pulverized caustic soda or potash then admixedunder conditions described bewith a hot freshly formed solution ofcaustic v alkali dissolved in a minimumamount of wa- Application filedMarch 19, 1930. Serial in. 437,273.

soaps can be thus produced which are perfectly saponified and do notcontain more than 0.025% free caustic alkali, the saponification beingmore complete than that obtained with cither'the boiled or the so-calledcold and semi-boiled processes of soap manufacture. The soap ismoreover, directly produced with a low water content and high soapcontent so that further drying is unnecessary.

The following more detailed description will further illustrate theprocess of the invention:

A suitable quantity of animal fat or vegetable oil is placed in a mixerwith revolving screw or paddle arrangement for bringing about intimatemixture of the fatty material and added ingredients. The temperature ofthe fatty material may range between about 100 and 150 F. According tothe saponification number of the fatty material, powdered caustic sodaof 76% sodium oxide (Na O) is carefully weighed and prepared for addingto the mixer. One part of such caustic soda can be dissolved in about0.4 to 0.7 parts of Water, thereby forming solutions of caustic alkalihaving concentrations of about per cent and 58 per cent respectively. AI

suflicient quantity of water for dissolving the weighed amount ofcaustic soda is added to and intimately mixed with the fatty material inthe mixer. Then the powdered caustic soda is slowly added under constantagitation or admixture until the mass presents a uniform emulsifiedappearance. Caustic alkali and water may 'be used in any ratio not lessthan one. An aqueous caustic alkali solution is saturated at ordinaryroom temperatures when equal parts of water and alkali are employed. Theuse of alkali solutions having concentrations lower than 50 per centinvolves the introduction of excess water which of course is one factorfound.

in ordinary soap manufacture which is avoided in my novel process.

This emulsified mass is withdrawn from the mixer as soon as it begins tothicken and is collected in a suitable receiving tank. In a few minutes,a self-heating process takes place. The mass develops such an intense rsaponification is about 40.7 parts.

heat that its temperature rises, e. g. to around 300 to 320 F, withformation of steam and raising of the mass in the container. Thisgeneration of heat and accompanying saponi- 5 tication processcontinues, according to the size of the batch, for a period of severalminutes, e. g. around 8 to 10 minutes, more or less, ai'ter which thenewly formed soap settles back in the container. After standing or afurther period of time, for example. around 25 to 30 minutes, thesaponification reaction is substantially completed, and the hot liquidsoap can then be removed from the container and cooled, for example, bypassing it between revolving water cooled iron rolls, revolving againsteach other. on which it is cooled and solidified, and from which it canbe scraped off or peeled off by knives closely set against the rolls.The soap 0 is thus directly produced in a flaked or shredded form andmay be either packed immediately as soap chips, or it may be pulverizedand formed into powdered or granulated soap. or it may be furthertreated, for example. by passing it through a plodding ma-- chine toform milled toilet soap.

,By using a limited amount of water, sufficient to dissolve the powderedcaustic soda, and mixing it with the fat before the caustic soda isadded, the caustic soda, when added, dissolves in water which isdistributed through the fat, forming a saturated or nearly saturatedsolution of caustic soda in the water which solution then acts upon thefat to bring about rapid and complete saponification. Owing to thelimited amount of water employed, there is no large amount of Water tobe removed. Some of the water 0 milled soap.

The process will be further illustrated by the following specificexamples. The parts are by weight:

Ewample 1-300 parts of corn oil of sapon ification number about 190 areput into a mixer. There is added and intimately admixed with the oil anamount of water which, together with that contained in. the powderedcaustic soda, will be suflicient for dissolving the caustic soda. Theamount'of water is in the neighborhood of 16.3 parts (in addition tothat in the caustic soda), and the amount of caustic soda required forIf the caustic soda is employed as 7 6% caustic containing 24% moisture,this moisture should container where the reaction will proceed and theemulsion will gradually begin and develop a great deal of heat, so much,in fact, that during the saponification or self-heating process, thenewly formed soap reaches a temperature above the boiling point of waterand rises considerably in the container.

After a certain time, the self-heating process stops and the soaprecedes in the container. At this stage it may be shredded between watercooled iron rollsagainst which a shredding knife is closely set, and theshredded soap can then be packaged for shipment.

Theoretically, the soap made according to the above-example would haveapproximately the following composition, expressed in terms of theingredients employed:

- P t Glycerides (corn oil) 300 8 Sodium oxide (Na O) 30.93 Water 26.06

The theoretical moisture content of a soap produced from theseingredients would be about 7.2%, but in practice it is somewhat lessbecause of the self-heating and resulting evaporation of moisture duringsaponification.

Emample 2.300 parts of cocoanut oil are treated in a manner similar tothat described in Example 1, except for the change in the amount ofcaustic soda required for the saponification, and the correspondingadjustment of the amount of water used.

It is also possible to replace part of the caustic soda with causticpotash in order to produce a product which will mill more smoothly andhave a finer texture. It is also possible. and in some cases desirable,that the smallest dissolving ratio of water be used in dissolving thecaustic soda before the mixing, that is. about 0.4 parts of water for 1part of caustic soda. in which case the admixture will be of the causticsoda solution with the glycerides. A solution of caustic. alkali ofalkali-water ratio of 1:0.4 may be obtained by taking advantage of theheat of solution of caustic alkali or by dissolving the alkali with theaid of heat. Such a solution is supersaturated with respect to ordinaryroom temperature.

It will thus be seen that the present in- I vention provides a simpleand rapid method of forming soaps v of high soap and low water contentin cake, chip or powder form, from fatty glycerides in which theingredients can be mixed cold, and the reaction carried rapidly tocompletion with selfheating by the heat of saponification. 1t willfurther be seen that the process results directly in the production ofcomplete-' ly saponified and relatively dry soap from low titreglycerides, with only a low or minimum moisture content, which can bedirectly converted into a merchantable form, for example, by rapidchilling on cooling rolls. Such soaps are firm, durable. less subject tohydrolysis and therefore not as likely to turn rancid as soaps of highmoisture content made by the common methods of manufacture abovereferred to. v The process presents many advantages, giving a marketablesoap in a short period of time, with saving of time, machinery, labor,heat, factory space, etc. 5

Different glycerides can be used formaking soaps according to thepresent process, and such g cerides may contain varylng percentages 0free fatty acid. The process can also be varied in the amountsandproportions of the ingredients employed without departing from thespirit and scope of the invention.

I claim: 1. A process for the manufacture of soap with caustic alkali,which comprises admixing with the fatty materials a iven weight ofcaustic alkali and a limited amount of water weighing not more thantheweight of said caustic alkali, emulsifying the resulting mixture, andcausin the saponification'to take place under seli content.

2. A process for the manufacture of soap,

which'comprises forminga supersaturated causing the saponi cation totake place wit substantial completeness and under selfneration of heatto produce directly a finis ed soap'produ'ct .of low. water content.

3. A process for the manufacture of soap,

which comprises admixing with the fatty materials a given weight ofcausticalkali' and a limited. amount of water weighing not more than theweight of said caustic alkali, andbringing about intimate admixturethereof with the fatty material, and causin the saponificationtotakeplace under se f-genereneration of heat to produce. directly afini ed soap of low water ation of heat to produce directly a finished

